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SCF Theory of Uniformly Charged Dendrimers: Impact of Asymmetry of Branching, Generation Number, and Salt Concentration
Macromolecules ( IF 5.5 ) Pub Date : 2020-08-20 , DOI: 10.1021/acs.macromol.0c00429 O. V. Shavykin 1 , I. M. Neelov 1 , O. V. Borisov 1, 2, 3 , A. A. Darinskii 1, 2 , F. A. M. Leermakers 4
Macromolecules ( IF 5.5 ) Pub Date : 2020-08-20 , DOI: 10.1021/acs.macromol.0c00429 O. V. Shavykin 1 , I. M. Neelov 1 , O. V. Borisov 1, 2, 3 , A. A. Darinskii 1, 2 , F. A. M. Leermakers 4
Affiliation
Polyelectrolyte dendrimers attract large interest and find multiple applications in many fields. The majority of theoretical and simulation works consider dendrimers with symmetrical branching where all spacers have the same length. In the present work, we for the first time systematically studied the effect of asymmetry of branching in flexible uniformly charged dendrimers on their structural properties. Lysine dendrimers with lysine amino acid residues as branching units and with spacers consisting of uniformly charged linear lysine (or arginine) peptides of two different lengths are an example of such dendrimers. The Scheutjens–Fleer self-consistent field approach was used to study the dendrimers with different asymmetries of branching and different generation numbers in solution at different salt concentrations. Three regimes—osmotic, salt-dominant, and quasi-neutral—were distinguished, and corresponding theoretical scaling dependencies have been verified. It was demonstrated that large-scale conformational properties practically do not depend on asymmetry of branching, but in the osmotic regime, the gyration radius weakly depends on it. The asymmetry of branching is manifested, however, in the internal structure of dendrimers, such as the radial distributions of monomer units, branching points, and terminal segments. The asymmetry of branching significantly affects also electrostatic properties of the dendrimers in the low-salt regime. While dendrimers with symmetric branching behave as a uniformly charged sphere with the maximum of electrostatic field on its surface, dendrimers with asymmetric branches behave as a sphere with decaying local charge density. The effective radius of an equivalent charged sphere increases and the surface electrostatic potential (ζ-potential) decreases with an increase of asymmetry of branching.
中文翻译:
均匀带电树状聚合物的SCF理论:支化,生成数和盐浓度的不对称性的影响
聚电解质树枝状聚合物引起了广泛的兴趣,并在许多领域中找到了多种应用。大多数理论和模拟工作都考虑具有对称分支的树枝状聚合物,其中所有间隔基的长度相同。在目前的工作中,我们第一次系统地研究了柔性均匀带电树枝状聚合物中支链不对称对其结构性质的影响。这种树状聚合物的例子是具有赖氨酸氨基酸残基作为分支单元并且具有由两个不同长度的均匀带电荷的线性赖氨酸(或精氨酸)肽组成的间隔基的赖氨酸树状聚合物。使用Scheutjens-Fleer自洽场方法研究了在不同盐浓度下溶液中具有不同支化不对称性和不同世代数的树枝状聚合物。三种体制-渗透,区分了盐为主和准中性,并验证了相应的理论比例依存关系。结果表明,大规模构象性质实际上不取决于分支的不对称性,但是在渗透状态下,回转半径几乎不依赖于它。但是,在树枝状聚合物的内部结构中表现出支化的不对称性,例如单体单元的径向分布,支化点和末端链段。在低盐条件下,支链的不对称性也显着影响树枝状聚合物的静电性能。具有对称分支的树枝状分子表现为表面上带静电场最大的均匀带电球,而具有不对称分支的树枝状分子表现为局部电荷密度下降的球。
更新日期:2020-09-09
中文翻译:
均匀带电树状聚合物的SCF理论:支化,生成数和盐浓度的不对称性的影响
聚电解质树枝状聚合物引起了广泛的兴趣,并在许多领域中找到了多种应用。大多数理论和模拟工作都考虑具有对称分支的树枝状聚合物,其中所有间隔基的长度相同。在目前的工作中,我们第一次系统地研究了柔性均匀带电树枝状聚合物中支链不对称对其结构性质的影响。这种树状聚合物的例子是具有赖氨酸氨基酸残基作为分支单元并且具有由两个不同长度的均匀带电荷的线性赖氨酸(或精氨酸)肽组成的间隔基的赖氨酸树状聚合物。使用Scheutjens-Fleer自洽场方法研究了在不同盐浓度下溶液中具有不同支化不对称性和不同世代数的树枝状聚合物。三种体制-渗透,区分了盐为主和准中性,并验证了相应的理论比例依存关系。结果表明,大规模构象性质实际上不取决于分支的不对称性,但是在渗透状态下,回转半径几乎不依赖于它。但是,在树枝状聚合物的内部结构中表现出支化的不对称性,例如单体单元的径向分布,支化点和末端链段。在低盐条件下,支链的不对称性也显着影响树枝状聚合物的静电性能。具有对称分支的树枝状分子表现为表面上带静电场最大的均匀带电球,而具有不对称分支的树枝状分子表现为局部电荷密度下降的球。